This invention relates to a radiographic depth gauge and a method of placing implants, and more particularly to a depth gauge and method which permits the precision placement of implants to their maximum depth in a jaw bone to assure a maximum strength supporting structure for one or more dental restorations. In addition, this invention relates to a depth gauge which also permits accurate parallel alignment of multiple implants so that a high aesthetic level is achieved with the look of natural dentition when the dental restorations are in place.
In order to restore dentition where there are one or more teeth missing, a modern technique is used which is called implant dentistry. Implant dentistry relies on the bonding of the implant to the jaw bone which is to receive one or more implants. A bore is formed in the bone by drilling and a part of an implant called a fixture is secured in the bone. The gums are then sutured and for a period of months the bone adheres to the fixture through osseointegration. After the fixture is secure in the bone, the gums are surgically opened and a restoration supporting abutment is secured to the fixture. Ultimately, a restoration is secured to each abutment. For a complete discussion of implant dentistry, see "Tissue - Integration Prostheses" by Branemark/Zarb/Albrektsson published by Quintessence Publishing Co., Inc. For purposes of describing the invention, the Bramemark implant will be described.
Currently, preoperative planning relies on radiographic procedures which lack the precision needed for highly accurate implant dentistry. Typically, a series of x-rays are taken in order to determine where and how to position implants in the jaw bone without damaging surrounding structures such as the nerves in the lower jaw bone and the sinuses adjacent the upper jaw bone. It is important that x-rays be produced by a standardized procedure so that x-rays taken at various times may be readily compared. In addition, the x-rays should produce accurate images which neither lengthen nor shorten the object being x-rayed, i.e. a tooth which is 8 mm above the top of the crest of the jaw bone should be 8 mm above on the x-ray. One well known method for achieving the foregoing is to use a Rinn Bite Block placement for holding the x-ray film and aligning the x-ray source perpendicular to the film. In addition to full mouth and smaller x-rays, some practitioners use CAT scans. CAT scans are both expensive and difficult to interpret. Accordingly, the conservative interpretation of CAT scans has led to implants being secured to less than the maximum depth available in the jaw bone, resulting in inadequate support for the restorations. The practitioner may also have stents fabricated to help in the visualization of where to place the implants.
The practitioner using his available information drills a hole to the selected depth, usually a little smaller than the final diameter of the implant and may insert a periodontal probe to measure the depth which is read visually with some room for error since the probes have handles which protrude from the mouth. Also, a guide may be placed in each hole and viewed to ascertain visually whether the holes are parallel to one another and oriented properly with respect to remaining teeth. Again this is a visual process and subject to error caused by among other things, the angle of looking into a patient's mouth.
While the foregoing x-rays, CAT scans, probes, stents and guides have been useful in permitting the practitioner to place implants fairly accurately, still further improvements in devices for assuring the accurate placement of implants would be beneficial. These improvements would be particularly beneficial if they both permit securely placing the implants in maximum depth bores and aligning the implants so that the restored dentition cosmetically is appealing.